The present disclosure relates to sensors incorporating waveguides in a three-dimensional (3D) substrate for use in the oil and gas industry. More specifically, the present disclosure relates to interferometry-based chemical sensors to measure fluid samples relevant in the oil and gas industry.
Chemical sensors using planar waveguide arrays in a Mach-Zehnder interferometer configuration have gained popularity for their high sensitivity. However, planar geometries are incompatible with the relatively large and circular cross-sections of optical fibers used to reach the depths of some wellbores in oil and gas exploration and extraction operations. In such downhole environments, the fragile complexion of planar waveguide arrays becomes a hindrance, as alignment procedures need to be enhanced. Also, planar waveguide arrays are more susceptible to stress, strain, high temperatures, and high pressures commonly encountered in downhole applications.